The invention relates to an improved apparatus for joining pipe or tubing to pipe fittings, valves and the like, and for disassembling the joined pipe.
Known methods for connecting a length of metal pipe or tubing to valves or pipe fittings such as elbows and tees include the use of threaded connectors, soldering, compression fitting, flaring, and welding. Non-metallic pipe, such as thermoplastic pipe, may also be joined by adhesives.
These methods are all subject to various drawbacks. Methods calling for the application of heat or force can be awkward and time consuming to practice in cramped and inaccessible areas, for example, areas in which residential plumbing is typically located. Soldering, welding and the like require the attention of a skilled worker using special tools to produce a good connection. Moreover, it is often difficult and time-consuming to disconnect a length of pipe from a fitting once they have been joined, and it is often not possible to disassemble the joint without damaging the pipe or the fitting to such an extent that they cannot later be rejoined.
Acceptable pipe joints are more difficult to make when the pipe is to carry a fluid under pressure. Even where threaded pipe and threaded connectors are used, greater skill is required to produce a stong and leakproof seal which will withstand the pressure rating of the pipe being joined. For proper sealing under pressure, washers or O-rings are often included in the joint. If the washer and pipe are made of dissimilar metals, they will sometimes undergo electrolysis in the presence of moisture in the joint or water and chemical agents flowing through the pipe. Electrolytic action leads to degradation of the washer, which can eventually cause the joint to leak and loosen the locking action of lock washers.
Some of the aforementioned drawbacks are overcome by the use of plastic pipe joined by adhesive. But plastic is unacceptable for some applications, such as hot water conduits in residential plumbing, and is difficult to connect directly to metal valve fittings without special adaptors. Moreover, once sealed with adhesive, plastic pipe joints cannot be readily undone.